docs: use portable paths in agents guide

Agent-Logs-Url: https://github.com/voku/Arrayy/sessions/f64d12ef-4929-4660-acd6-f6f4d81e2028

Co-authored-by: voku <264695+voku@users.noreply.github.com>

Author: Copilot

AGENTS.md

@@ -83,8 +83,8 @@ This reads `src/Arrayy.php` docblocks and `build/docs/base.md`, then writes `REA
 
 - Rebuild the README with `php build/generate_docs.php`
 - That script requires both:
-  - `/home/runner/work/Arrayy/Arrayy/vendor/autoload.php`
-  - `/home/runner/work/Arrayy/Arrayy/build/vendor/autoload.php`
+  - `vendor/autoload.php`
+  - `build/vendor/autoload.php`
 - On this branch, rerunning the generator completed successfully and did not change `README.md`
 - `AGENTS.md` is manually maintained and should be updated separately after README regeneration when task-specific context needs to be preserved